The Arch of Malborghetto lies 20km north of Rome at the former intersection between two Roman roads, resulting in four gigantic arches: one in each side. Today, the structure has been converted into a museum. This is the view from the south-east.

Why was a victory monument erected 20km from Rome? David J Breeze explores the extraordinary circumstances that led to an unsung triumphal arch at Malborghetto.

For the last 30 years I have visited Rome roughly every other year, taking my sons and now my grandchildren to see this marvellous city, usually staying in the comfortable Santa Chiara Hotel beside the Pantheon. I maintain a list of places that I have not yet visited, but one that was not on it until a few weeks ago was the Arch of Malborghetto, some 20km north of the city. I managed to escape my family and visit it in early May.

Surprisingly, the arch does not feature in any of the books on Constantine by ancient historians that sit on my shelves, and it escapes attention in most of the archaeological guides, though it does make an appearance in Rome and Environs: An Archaeological Guide, by Filippo Coarelli.

The south and west faces of the monument, with two bricked-up arches clearly visible. Was this the site of Constantine’s camp before the Battle of the Milvian Bridge?

Because the monument was located where two major roads cross – the Via Flaminia and the Via Veientana – it has arches on all four sides. Over the centuries, the structure has been radically altered, with the arches bricked up in order to turn it into a dwelling. After a colourful history, the building is now a museum, with sculpture and inscriptions laid out in a little park to one side.

Fritz Töbelmann first studied the arch shortly before the First World War, which claimed his life. He recorded a brick stamp of Diocletian in its structure, an observation that provided useful dating evidence. In size – 14.86m by 11.87m – it is similar to the Arch of Janus in the Forum Boarium, which appears to date to the reign of Constantine’s son, Constantius II (337-361). Originally it would have been clad with marble, some of which survives on the north side. The big mystery concerning the arch, though, is why is it there? Although Constantine’s consolidation of power involved a miraculous – reputedly literally so – victory near Rome at the Battle of the Milvian Bridge, the location of this arch does not coincide with the scene of the fighting.

Töbelmann concluded that the arch marked the site of Constantine’s camp before the battle. Subsequently, it was suggested this was where the emperor had a vision that changed the course of Roman history. To understand the significance of the arch, it is necessary to recall the events of Constantine’s march on Rome.

Vision of victory

The Milvian Bridge today. Although heavily outnumbered, Constantine took the fight to Maxentius and his gamble paid off.

Constantine was proclaimed emperor in York on 25 July 306, following the death of his father Constantius I. Just six years later, in 312, Constantine set out from Gaul to seek a showdown with his fellow emperor, Maxentius, who seemed secure behind the Aurelian Walls of Rome. By late October 312, Constantine had subdued northern Italy and was camped to the north of the city. At this point, we have to turn to the ancient sources. Lactantius, writing only two or three years after the event, stated that the night before the battle Constantine was instructed in a dream to place the Christian sign on his army’s shields before he went into battle. Eusebius, writing nearly 30 years later, recorded two events. The first was a statement given to him by Constantine under oath that, shortly after midday, he and his army saw in the sky over the position of the sun, a trophy shaped like a cross and bearing the inscriptions ‘conquer by this’. The vision was later followed by a dream in which he was told to make a likeness of the sign to protect him. As a result, Constantine had the Christian symbol of the Chi Rho placed on the military flags.

Peter Weiss has analysed the ancient sources and descriptions of celestial phenomena and persuasively argued that there were two separate events. The first was the vision, which Weiss related to a vision that Constantine was recorded seeing two years earlier in 310. The description of the vision was similar to accounts of sun halos, with cross-shaped arms radiating out from the sun. The words ‘conquer by this’ were an interpretation of the lights of the halo, or ‘a pictogram’ as Weiss put it.

Victory at the Milvian Bridge delivered the Roman Empire to Constantine – whose head is shown here with David’s wife Pam providing a sense of scale.

The second event was the dream that Lactantius stated occurred the night before the battle. It would appear that Eusebius has squeezed the two incidents together, though he himself recorded that Constantine had considered the meaning of the vision for a long time. Weiss’s analysis also allows us to make sense of the creation of the labarum: the flag bearing the Christian symbol. Eusebius stated that the original labarum was made after the dream, but this seems unlikely as it incorporated gold and precious stones. There would have been more time to craft this sumptuous statement of allegiance if the vision had occurred in Gaul.

There is one final important piece of evidence. Constantine was taking a gamble in attacking Maxentius’s home base, and acting against the advice of his generals. As he approached Rome, there had been some fighting and Maxentius had the upper hand. It was at this point that Constantine took the decisive step of enlisting the support of the Christian god. It is hardly surprising, therefore, that after his success – against the odds – Constantine would erect that archetypal Roman victory symbol, a triumphal arch, at the very spot where he had taken the decision that would lead him on to conquest of the entire empire.

This article appeared in issue 85 of Current World Archaeology. To find out more about subscribing to the magazine, click here.